The overarching goal of the proposed study is to expand scientific knowledge regarding the correlates of overreactive parenting, with an eye toward improving parenting interventions that target child conduct problems. Drawing from a biopsychosociai model, hypotheses are offered about how parents' thoughts and feelings about, and physiological responses to, their children relate to harsh discipline. Specific aims are as follows: Aim 1 is to test the generalizability of negative sentiment override from dysfunctional marriages to troubled mother-child relationships. A mediated model in which previous child externalizing problems, preinteraction child-related sentiment, expectations, as well as anticipatory affective and psychophysiological reactivity are associated with negatively biased appraisals of child behavior and overreactive discipline is hypothesized. Aim 2 is to test the relation between harsh parenting and psychophysiological reactivity to parent-child conflict, extending physiological assessment to live interactions of mothers and their toddlers, and including the assessment of vagal reactivity (as well as electrodermal reactivity). These relations will be tested in a sample of 100 mother-toddler dyads in which the toddlers are exhibiting varying degrees of incipient externalizing problems.